PROVINCE ADVISES SPRING RUN-OFF HAS STARTED IN MOST AREAS OF MANITOBA
– – – Red River Peak Expected to Move from Emerson to Winnipeg in Next Five to Six Days
The Hydrologic Forecast Centre at Manitoba Infrastructure and Transportation advises that spring run-off due to snowmelt has started in most of the southern, southwest, southeast and Interlake regions.
Above-freezing temperatures earlier this month in southern and central Manitoba, adjacent provinces and the United States have led to an early spring melt. The recent steep temperature rise resulted in rapid snowmelt rates.
The Red River is expected to peak at Emerson between March 18 to 20 and at Ste. Agathe March 19 to 21. The crest will arrive in Winnipeg March 20 to 22, resulting in a James Avenue crest between 16 and 17 feet. Potential ice jams could make this peak higher.
The Red River is expected to remain within its banks, not requiring any community dike closures and the forecast peak will not necessitate the use of the floodway, although some water may spill naturally over the floodway entrance.
Peak spring run-off has already entered the Pembina River and tributaries, the Souris River and its tributaries, as well as for some tributaries of the Red River.
Spring run-off and a rise in levels are occurring for the Roseau, Fisher, Icelandic and Whitemouth rivers.
• Most rivers and creeks in the western part of the province, including those in the Duck Mountain and Riding Mountain areas and the central and northern portion of the Assiniboine River, have also started to see minor spring run-off.
• The majority of the spring run-off has yet to occur in these areas because of a slower snowmelt rate.
• Frozen or blocked culverts in drains and small tributaries may cause localized overland flooding.
• It is expected levels will remain within the bank for all rivers and creeks, although ice jams could occur and raise levels significantly.
Northern and Northwest Regions
• Temperatures have generally been below freezing throughout the northern and northwest regions, with short periods of temperatures above 0 C. Snowmelt and spring run-off have been minor and a larger melt and run-off are yet to come.
• The Saskatchewan River, Carrot River and the Saskatchewan portion of the Assiniboine River watersheds have substantial amounts of snow on the ground.
• Recorded winter precipitation in these areas is near normal to below normal, soil moisture before freeze-up was above normal and the run-off potential is expected to be near normal.
• Therefore, the flood risk in these regions is minor to moderate.
• Inflow into the Shellmouth Reservoir is forecast to be between 350,000 acre-ft. to 600,000 acre-ft. for lower and upper decile conditions respectively. The Shellmouth Liaison Committee members are regularly meeting to discuss and advise on the operation of the dam.
• Most lakes are expected to be below the flood stage after the spring run-off.
• Most major lakes, including lakes Manitoba, Winnipegosis and St. Martin have not seen rises due to the spring run-off. Most of the lakes are expected to be below flood stage after the spring run-off, except Whitewater Lake, which is already above the long-term normal level.
• Most of the lakes are still frozen and the effect of wind and ice pile up is negligible.
• Ice has started to move in Winnipeg and on the Red River in the Selkirk area but ice jams on the Red River are still possible.
• Heavy ice is still present on most areas of the Assiniboine River.
• Ice is still in place for most other rivers including the Fisher, Icelandic and Whitemud rivers.
• There is still a chance of localized flooding due to ice jams on the Saskatchewan River at The Pas and the Carrot River, when the melt starts.
Current and Future Weather
• The recent snow and rain between March 10 and 17 resulted in five to 40 mm of precipitation.
• The Swan River area and southeast Manitoba received the majority of the precipitation, which has slightly increased the peak run-off on the Red River. Snow has not melted in other areas.
• The short-term weather forecast indicates minimal precipitation in the next seven to 10 days throughout most areas across the province.
• The short-term weather forecast also indicates daily temperatures will remain near 0 C or slightly below 0 C for the next 10 days for most parts of central and southern Manitoba.